How to find out in UBUNTU what kind of request goes to the network?

Question

ubuntu

I study the network settings in ubuntu)
Blocked all connections:
iptables -A OUTPUT -o eth0 -j DROP
but this request passes:
21:51:40.487688 IP6 fe80::a62:66ff:fe21:3a7.mdns > ff02::fb. mdns: 0 [2q] PTR(QM)? _ipps._tcp.local. PTR(QM)? _ipp._tcp.local. (45)
What is this request and why is it not blocked?

Answer 1

Because it's on IPv6, and you're blocking IPv4. IPv6 has its own rule table:
ip6tables -A OUTPUT -o eth0 -j DROP
The "multicast dns" request is part of Zeroconf.